Coast Redwood with Brown Foliage

My Coast Redwood has brown foliage, does it need more water?

While it is true that Coast Redwoods need summer irrigation, in late summer (August or September) they will be showing brown foliage as the tree gets rid of some of the older growth. But a brown redwood could also be a sign that the tree needs more water. So how can you tell?

Look at your tree and observe where the brown foliage is.

If the brown foliage is only the inner foliage on branches and the foliage at the tips of the branches is lush and green, it is just the normal shedding of foliage that Coast Redwoods do in late summer. You probably don’t need to worry about irrigation.

redwood branch with green new growth and brown older foliage

But if the tree is brown all over or at the ends of the branches and the top of the tree, it is likely to be lack of water. This may be an urgent situation for the tree and damage or death can ensue if the tree goes too long without water. We recommend that you check the soil moisture very soon to verify that it needs water. If you find that the soil is dry, apply water until the soil is moist 18-24” deep.

How to check the soil moisture: Use an inexpensive moisture meter (available at nurseries and hardware stores), big screwdriver or sturdy dowel, or dig a hole in the soil and look at it. You need to check several spots near the edge of the canopy. The soil should be moist there.

  • On a moisture meter it should show moist on the gage. Check several locations and be careful pushing it into the soil as the probes are usually not very sturdy.
  • If you push a big screwdriver or dowel into the soil and it won’t go, it’s probably too dry. If you push it is and it comes out with bits of soil clinging to it, its moist. If it comes out muddy that’s too wet. Try again a day or two later to see if the soil is not moist not wet.
  • If you dig a hole and the soil is hard and dry like a cracker-your tree needs water, if it mud-you tree has too much water so you need to allow the soil to dry between irrigations. Moist soil will be more like cake than pudding (kind of a heavy cake and I wouldn’t recommend tasting it!)

Coast Redwoods are kind of Tree Wimps here in our hot summer climate. They naturally grow in cooler, moister areas of California like the northern Coast Ranges where they do not need additional summer irrigation. But here in the hot California Central Valley, they will suffer and usually die without reliable irrigation. If you have a Coast Redwood that has had damage because of lack of water, all is not lost because they frequently come back after they get water. But you should consult a qualified arborist to assess the tree because if it has dead branches, they need to be removed before they decay and break.